Philippians as the epistle of proper Christian experience

In the epistle to the Philippians we find much more of christian
experience, and the development of the exercise of the heart, than
in the generality of the epistles. It is in fact proper christian
experience. Doctrine and practice are found in them all, but, with
the exception of the second to Timothy which is of another nature,
there is none that contains like this, the expression of the
Christian's experience in this toilsome life, and the resources
which are open to him in passing through it, and the motives which
ought to govern him. We may even say that this epistle gives us the
experience of christian life in its highest and most perfect
expression -- say, rather, its normal condition under the power of
the Spirit of God. God has condescended to furnish us with this
beautiful picture of it, as well as with the truths that enlighten
us, and the rules that direct our walk.

The occasion for the epistle; Paul in prison; his need and the
Philippians' love

The occasion for it was quite natural. Paul was in prison, and
the Philippians (who were very dear to him, and who, at the
commencement of his labours, had testified their affection for him
by similar gifts) had just sent assistance to the apostle by the
hand of Epaphroditus at a moment when, as it appears, he had been
for some time in need. A prison, need, the consciousness that the
assembly of God was deprived of his watchful care, this expression
on the part of the Philippians of the love that thought of him in
his necessities, although at a distance -- what could be more
adapted to open the apostle's heart, and lead to his expressing the
confidence in God that animated him, as well as what he felt with
regard to the assembly, unsupported now by his apostolic care, and
having to trust God Himself without any intermediate help? And it
was most natural that he should pour out his feelings into the
bosom of these beloved Philippians, who had just given him this
proof of their affection. The apostle therefore speaks more than
once of the Philippians' fellowship with the gospel: that is to
say, they took part in the labours, the trials, the necessities
which the preaching of the gospel occasioned to those who devoted
themselves to it. Their hearts united them to it -- like those of
whom the Lord speaks who received a prophet in the name of a
prophet.